The court heard that when jail guards apprehended Fowler, he immediately admitted his guilt and said: “It’s a fair cop. I was tiring of his mind games.”

Fowler, now of HMP Glenochil, pleaded guilty to a single charge of serious assault before Sheriff Elizabeth Jarvie QC.

Depute procurator fiscal Dev Kapadia told the court that Fowler walked into Dalmar’s cell at Saughton and plunged a sharp object into the man’s cheek. Prison guards were alerted after hearing Dalmar’s loud screams. Meanwhile, Fowler walked out of the cell and disposed of the weapon.

Defence solicitor Jim Wardlaw told the court that his client did not like Dalmar.

Sentence was deferred until later this month in order for the court to obtain reports.